Understanding Pointers in C Programming: Declaration, Address, and Dereferencing, Slides of Computer Fundamentals

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Today’s Lecture

 Pointers

• Declaring a pointer
• Getting address of a variable
• Dereferencing a pointer

 Pointers and arrays

 Pointers and functions

Pointers

 Pointers

• Powerful and provide faster access

 C uses pointers in three different ways

• Simulate call-by-reference
• Access information stored in arrays (Close

relationship with arrays and strings)

• Dynamic Memory Allocation

 Data structures that can grow or shrink

Address of a variable &

int x = 10;

printf("Address of x = %p\n", &x);

Output:

Address of x = 0040FE

%p outputs the memory location as a hexadecimal integer

Pointers

x

0040FE

Location Address of x

Declaring a pointer

int *myPtr ;

Variable myPtr is pointer to an integer

* means pointer to

Declaring pointers

int *ptr1 , *ptr2 , *ptr3 ;

Declaring pointers

*int ptr , x , a [ 10 ] ;

Declaring Pointers

double *dPtr ;

char *cPtr ;

float *fPtr;

Getting address of a variable

xPtr = &x;

 xPtr gets address of x

 xPtr “points to” x

Pointer example

xPtr

x

5

xPtr

500000 600000

x

600000 5

Address of x

is value of

xPtr

Dereferencing Operator *

*ptr is read as

“The value of whatever ptr points to”

*z = xPtr + 2 ;

Dereferencing a pointer

Accessing the variable

pointed to by a pointer